Practice free →
HomeScottish National 5PhysicsMirrors and Lenses › In diagrams of mirrors and lenses, what is meant…

In diagrams of mirrors and lenses, what is meant by the central axis?

AThe distance from a mirror to its centre of curvature
BA line perpendicular to the centre of a lens or mirror
CThe angle between an incident ray and the normal
DThe reciprocal of a lens or mirror's focal length
Answer & Solution
Correct answer: B. A line perpendicular to the centre of a lens or mirror
1. The central axis is defined as a line perpendicular to the centre of a lens or mirror, extending in both directions. 2. Focal length, focal point and object and image distances are all measured with reference to this axis. 3. The distance to the centre of curvature is a separate quantity, R, not the axis itself. 4. The angle to the normal describes reflection or refraction at a point, which is a different concept from this axis. _Source: OpenStax Physics (CC BY 4.0), Ch 16 "Mirrors and Lenses", section 16.1 Reflection_
Solve this in the app — Scottish National 5 practice & 24k+ MCQs →
Related questions